Today we take for granted the ability to watch HDTV on large screens in our homes, see stunning digital cinema at super high resolution in the theatre, and stream high quality video to our smartphones, tablets and computers. It wasn’t always this way…
One of the first attempts at recording and playing video content (with audio as well) – all previous video distribution was completely live in real time – was a British system: the Vision Electronic Recording Apparatus (VERA). The development of this device began in 1952 by the BBC, under project manager Dr. Peter Axon.
All previous recording technology of that time was used for audio. Of course, only analog techniques were available then. At a high level, the recorders used open-reel magnetic tape that passed over a fixed record/playback head. Although there were several formats for audio recording in use by the 1950’s – common ones used professionally moved the tape at 15ips (inches per second) to record frequencies up to 16kHz – there were no video recording devices.
Video signals, even monochrome, require a much higher bandwidth. The relatively low-resolution cameras of that day (405 tv lines vertically) needed about 3MHz to record the fine detail in the picture. This is roughly 200x the maximum frequency recorded by audio tape machines of that time. Essentially, in order to record a signal on magnetic tape using stationary heads, either the head gap must be made smaller, or the tape must move faster.
Limitations in materials science in the 1950’s, as well as other complex issues of recording head design essentially dictated that the tape needed to move much faster to record video. For the VERA system, the BBC used 52cm (20”) reels of magnetic tape that moved past the stationary record/playback head at 5.08 meters per second (16.7 ft. per sec.!) That’s about 20x faster than audio tape – quite a mechanical achievement for that time.
VERA was capable of recording about 15 minutes (e.g. 4572 meters) of 405-line black-and-white video per reel, and the picture tended to wobble because the synchronizing pulses that keep the picture stable were not recorded accurately enough.
In order to cope with 625-line PAL or SECAM colour transmissions VERA would likely have required an even faster, and possibly unfeasible, tape speed.
Development began in 1952, but VERA was not perfected until 1958, by which time it had already been rendered obsolete by the Ampex quadruplex video recording system. This used 5cm (2”) wide tapes running at a speed of 38cm/s (15ips). The rapid tape-to-head speed was achieved by spinning the heads rapidly on a drum: the system used, with variations, on all video tape systems ever since, as well as DAT.
The BBC scrapped VERA and quickly adopted the Ampex system. It has been suggested that the BBC only continued to develop VERA as a bargaining tool, so it would be offered some of the first Ampex machines produced in unstated exchange for abandoning further work on a potential rival.
The only VERA recordings that survive are film telerecordings of the original demonstration. Even if some of the original tape had survived there would be no way of playing it back today. Rather the film kinescopes were transferred using modern film scanning technology to a digital file, one of which is reproduced here.
Tagged: 405-line, BBC, VERA, vtr